Preparation And Anticorrosion Performance Of Stimulus Response Controlled Release System Based On ZIF-8

Metal corrosion can greatly change the physical and chemical properties of metal materials,and has a significant impact on the environment and economy.However,the traditional coating corrosion protection technology has the problem of short service life,which limits the application and development of coating materials.In recent years,intelligent anticorrosive coatings with active protection capabilities have gradually received attention from researchers because they can repair themselves like biologica l tissues and achieve long-term anti-corrosion to metals.In this paper,a multifunctional stimulus-responsive controlled release system using metal organic framework material(ZIF-8)as a nano-container was designed and prepared,and it was applied to waterborne epoxy coating to prepare intelligent anticorrosive coating,the ability of nanofillers to control the release of corrosion inhibitors in response to p H stimuli and the anti-corrosion performance of composite coatings on carbon steel substrates were studied,and the anti-corrosion mechanism of the coatings was explored.The main research contents and conclusions are as follows:(1)Preparation and properties of tannic acid modified BTA@ZIF-8 material.In this chapter,a one-pot method was used to successfully realize the efficient encapsulation of corrosion inhibitor 1H-benzotriazole molecule(BTA)in ZIF-8(BTA@ZIF-8,ZB-x),ZIF-8 shows good load capacity for BTA.The effect of the addition amount of BTA on product size,morphology and BTA loading rate is studied,and the influence mechanism of BTA is illustrated;the surface modification of ZB-2was carried out with tannic acid(TA),and the properties of controllable realease corrosion inhibitor of the material(BTA@ZIF-8@tannic acid,ZBT)were investigated under different pH conditions.The results showed that the surface modification of tannic acid significantly enhanced the dispersibility of ZB-2 in the coating,and the release of BTA showed a obvious pH dependence.Electrochemical impedance test(EIS),salt spray corrosion test and salt water immersion test were used to evaluate the corrosion resistance of the coating.The results showed that ZBT could effectively enhance the long-term corrosion resistance performance of the coating and endow it with excellent self-healing properties.These excellent properties are related to the good dispersibility of ZBT in the coating,the barrier effect of the hydrophobic substances formed by the secondary reaction of Zn²⁺,2-methylimidazole and BTA in aqueous solution,and the corrosion inhibition effect of BTA and tannic acid.(2)Preparation and properties of PDA modified Ce-doped ZIF-8 composite.The combination of corrosion inhibitor synergy and smart nanocontainers i s expected to further improve the service cycle of the coating.Based on the synthetic route of BTA@ZIF-8 mentioned in the previous chapter,the Ce-doped composite material BTA@Zn/Ce-ZIF-8(ZB-Ce)was prepared by introducing Ce into ZIF-8 using the one-pot method.The simultaneous loading of two corrosion inhibitors(BTA and Ce ions)by ZIF-8,and the surface modification of ZB-Ce(10:1)using polydopamine(PDA)to obtain ZBP-Ce.SEM,XRD,FT-IR,XPS were used to characterize the physical and chemical properties of the prepared materials.The results showed that ZBP-Ce had good p H stimulus response release characteristics,and showed a faster release rate of BTA.In addition,the surface modification of PDA significantly improved the compatibility of ZB-Ce with the coating.EIS results showed that BTA and Ce ions have a synergistic corrosion inhibition effect.Compared with the undoped epoxy coating,ZBP-Ce/EP coating still does not corrode after after immersion for 35days,and its resistance value is about 2 orders of magnitude higher than that of the undoped epoxy coating,which can be attributed to the barrier effect of the well-dispersed ZBP-Ce nanoparticles and the efficient synergistic effect of the corrosion inhibitor.